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Title: Pumpernickel Valley Geothermal Project Thermal Gradient Wells

Abstract

The Pumpernickel Valley geothermal project area is located near the eastern edge of the Sonoma Range and is positioned within the structurally complex Winnemucca fold and thrust belt of north-central Nevada. A series of approximately north-northeast-striking faults related to the Basin and Range tectonics are superimposed on the earlier structures within the project area, and are responsible for the final overall geometry and distribution of the pre-existing structural features on the property. Two of these faults, the Pumpernickel Valley fault and Edna Mountain fault, are range-bounding and display numerous characteristics typical of strike-slip fault systems. These characteristics, when combined with geophysical data from Shore (2005), indicate the presence of a pull-apart basin, formed within the releasing bend of the Pumpernickel Valley – Edna Mountain fault system. A substantial body of evidence exists, in the form of available geothermal, geological and geophysical information, to suggest that the property and the pull-apart basin host a structurally controlled, extensive geothermal field. The most evident manifestations of the geothermal activity in the valley are two areas with hot springs, seepages, and wet ground/vegetation anomalies near the Pumpernickel Valley fault, which indicate that the fault focuses the fluid up-flow. There has not been any geothermalmore » production from the Pumpernickel Valley area, but it was the focus of a limited exploration effort by Magma Power Company. In 1974, the company drilled one exploration/temperature gradient borehole east of the Pumpernickel Valley fault and recorded a thermal gradient of 160oC/km. The 1982 temperature data from five unrelated mineral exploration holes to the north of the Magma well indicated geothermal gradients in a range from 66 to 249oC/km for wells west of the fault, and ~283oC/km in a well next to the fault. In 2005, Nevada Geothermal Power Company drilled four geothermal gradient wells, PVTG-1, -2, -3, and -4, and all four encountered geothermal fluids. The holes provided valuable water geochemistry, supporting the geothermometry results obtained from the hot springs and Magma well. The temperature data gathered from all the wells clearly indicates the presence of a major plume of thermal water centered on the Pumpernickel Valley fault, and suggests that the main plume is controlled, at least in part, by flow from this fault system. The temperature data also defines the geothermal resource with gradients >100oC/km, which covers an area a minimum of 8 km2. Structural blocks, down dropped with respect to the Pumpernickel Valley fault, may define an immediate reservoir. The geothermal system almost certainly continues beyond the recently drilled holes and might be open to the east and south, whereas the heat source responsible for the temperatures associated with this plume has not been intersected and must be at a depth greater than 920 meters (depth of the deepest well – Magma well). The geological and structural setting and other characteristics of the Pumpernickel Valley geothermal project area are markedly similar to the portions of the nearby Dixie Valley geothermal field. These similarities include, among others, the numerous, unexposed en echelon faults and large-scale pull-apart structure, which in Dixie Valley may host part of the geothermal field. The Pumpernickel Valley project area, for the majority of which Nevada Geothermal Power Company has geothermal rights, represents a geothermal site with a potential for the discovery of a relatively high temperature reservoir suitable for electric power production. Among locations not previously identified as having high geothermal potential, Pumpernickel Valley has been ranked as one of four sites with the highest potential for electrical power production in Nevada (Shevenell and Garside, 2003). Richards and Blackwell (2002) estimated the total heat loss and the preliminary production capacity for the entire Pumpernickel Valley geothermal system to be at 35MW. A more conservative estimate, for the hot spring area only, was presented by GeothermEx Inc. (2004), which projected that power generation capacities for the Pumpernickel Valley site are 10 MW-30yrs minimum (probablility of >90%), and most likely 13 MW-30yrs.« less

Authors:
Publication Date:
Research Org.:
Nevada Geothermal Power (formerly Noramex Corp)
Sponsoring Org.:
USDOE - Energy Information Administration (EI)
OSTI Identifier:
883167
Report Number(s):
GREDIII - Phase I
TRN: US200719%%252
DOE Contract Number:
FG36-04GO14340
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
15 GEOTHERMAL ENERGY; BOREHOLES; ELECTRIC POWER; EXPLORATION; GEOCHEMISTRY; GEOMETRY; GEOTHERMAL FIELDS; GEOTHERMAL FLUIDS; GEOTHERMAL GRADIENTS; GEOTHERMAL RESOURCES; GEOTHERMAL SYSTEMS; GEOTHERMOMETRY; HEAT SOURCES; HOT SPRINGS; MAGMA; PLUMES; POWER GENERATION; TECTONICS; TEMPERATURE GRADIENTS; Geothermal Legacy; Pumpernickel Valley Nevada Geothermal Drilling Hot Springs Resistivity Geochemistry

Citation Formats

Z. Adam Szybinski. Pumpernickel Valley Geothermal Project Thermal Gradient Wells. United States: N. p., 2006. Web. doi:10.2172/883167.
Z. Adam Szybinski. Pumpernickel Valley Geothermal Project Thermal Gradient Wells. United States. doi:10.2172/883167.
Z. Adam Szybinski. Sun . "Pumpernickel Valley Geothermal Project Thermal Gradient Wells". United States. doi:10.2172/883167. https://www.osti.gov/servlets/purl/883167.
@article{osti_883167,
title = {Pumpernickel Valley Geothermal Project Thermal Gradient Wells},
author = {Z. Adam Szybinski},
abstractNote = {The Pumpernickel Valley geothermal project area is located near the eastern edge of the Sonoma Range and is positioned within the structurally complex Winnemucca fold and thrust belt of north-central Nevada. A series of approximately north-northeast-striking faults related to the Basin and Range tectonics are superimposed on the earlier structures within the project area, and are responsible for the final overall geometry and distribution of the pre-existing structural features on the property. Two of these faults, the Pumpernickel Valley fault and Edna Mountain fault, are range-bounding and display numerous characteristics typical of strike-slip fault systems. These characteristics, when combined with geophysical data from Shore (2005), indicate the presence of a pull-apart basin, formed within the releasing bend of the Pumpernickel Valley – Edna Mountain fault system. A substantial body of evidence exists, in the form of available geothermal, geological and geophysical information, to suggest that the property and the pull-apart basin host a structurally controlled, extensive geothermal field. The most evident manifestations of the geothermal activity in the valley are two areas with hot springs, seepages, and wet ground/vegetation anomalies near the Pumpernickel Valley fault, which indicate that the fault focuses the fluid up-flow. There has not been any geothermal production from the Pumpernickel Valley area, but it was the focus of a limited exploration effort by Magma Power Company. In 1974, the company drilled one exploration/temperature gradient borehole east of the Pumpernickel Valley fault and recorded a thermal gradient of 160oC/km. The 1982 temperature data from five unrelated mineral exploration holes to the north of the Magma well indicated geothermal gradients in a range from 66 to 249oC/km for wells west of the fault, and ~283oC/km in a well next to the fault. In 2005, Nevada Geothermal Power Company drilled four geothermal gradient wells, PVTG-1, -2, -3, and -4, and all four encountered geothermal fluids. The holes provided valuable water geochemistry, supporting the geothermometry results obtained from the hot springs and Magma well. The temperature data gathered from all the wells clearly indicates the presence of a major plume of thermal water centered on the Pumpernickel Valley fault, and suggests that the main plume is controlled, at least in part, by flow from this fault system. The temperature data also defines the geothermal resource with gradients >100oC/km, which covers an area a minimum of 8 km2. Structural blocks, down dropped with respect to the Pumpernickel Valley fault, may define an immediate reservoir. The geothermal system almost certainly continues beyond the recently drilled holes and might be open to the east and south, whereas the heat source responsible for the temperatures associated with this plume has not been intersected and must be at a depth greater than 920 meters (depth of the deepest well – Magma well). The geological and structural setting and other characteristics of the Pumpernickel Valley geothermal project area are markedly similar to the portions of the nearby Dixie Valley geothermal field. These similarities include, among others, the numerous, unexposed en echelon faults and large-scale pull-apart structure, which in Dixie Valley may host part of the geothermal field. The Pumpernickel Valley project area, for the majority of which Nevada Geothermal Power Company has geothermal rights, represents a geothermal site with a potential for the discovery of a relatively high temperature reservoir suitable for electric power production. Among locations not previously identified as having high geothermal potential, Pumpernickel Valley has been ranked as one of four sites with the highest potential for electrical power production in Nevada (Shevenell and Garside, 2003). Richards and Blackwell (2002) estimated the total heat loss and the preliminary production capacity for the entire Pumpernickel Valley geothermal system to be at 35MW. A more conservative estimate, for the hot spring area only, was presented by GeothermEx Inc. (2004), which projected that power generation capacities for the Pumpernickel Valley site are 10 MW-30yrs minimum (probablility of >90%), and most likely 13 MW-30yrs.},
doi = {10.2172/883167},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 2006},
month = {Sun Jan 01 00:00:00 EST 2006}
}

Technical Report:

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  • The purpose of this investigation is to estimate vertical fluid flux rates in saturated units penetrated by selected wells at the Nevada Test Site (NTS) using geothermal gradient data. Estimates of vertical fluid flux rates are critical in developing models for contaminate flow within, recharge potential to, and discharge from the groundwater system at the NTS. If temperature in the well is in equilibrium with the surrounding rocks, it is possible to detect the vertical flow of groundwater from the well`s thermal profile. Heat in the subsurface is transported by conduction through the rock and by advection caused by subsurfacemore » water movement. Units in which vertical flow is occurring will produce a curve in the thermal profile within the well. Prior to the implementation of the Underground Test Area Remedial Investigation/Feasibility Study (UGTA RI/FS), investigation of thermal data from wells at the NTS was hindered by the completion of wells as open holes or without casing cemented in place. The open-hole type of completion allows cross-flow within the wellbore which can yield information about relative pressures between connected aquifers, but which renders thermal gradient data essentially useless, or at best highly suspect for interpreting in situ groundwater movement. Wells recently completed in the Department of Energy (DOE) Environmental Restoration (ER) Program have been completed with casing cemented to the surface (to prohibit cross-flow between units in the annular space between the casing and the wellbore) and with completion zones open to a single hydrologic horizon. This type of completion results in temperature gradient profiles more representative of actual thermal conditions in the units penetrated by the well. Results are presented of temperature profiles of 3 wells located in the Death Valley Groundwater Basin, outside the southern border of the NTS.« less
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